1. Field of the Invention
This application relates to the field of capacity allocation on networks. More specifically, to the allocation of capacity on Internet protocol (IP) networks utilizing VoIP technology.
2. Description of Related Art
Communication services today are generally based on either the public switched telephone network (PSTN), which provides circuit-switched voice servers, real-time faxing, and central office (CO)-based voice mail, or the Internet protocol (IP)-based Internet, intranet, or extranet systems, which provide services such as e-mail.
The PSTN and the IP-based systems rely on different architectures and protocols. The PSTN refers to a collection of interconnected systems operated by the various telephone companies (telcos) and post telephone and telegraph administrations (PTTs) around the world. Although the PSTN was originally based on human-operated analog circuit switching systems, it has progressed through electromechanical switches, and has currently been made almost completely digital. As this change has progressed, however, the style of transmission has not changed. PSTN systems use dedicated circuits. That is, when a phone number is dialed, switches in the network lock-up a dedicated circuit that can only be used by that phone call and exist until that phone call is terminated. Thus, even when there is no information to carry as part of the transmission (e.g. the callers are silent) the circuit is still in use by the call.
IP networks work on a different principle. Instead of sending transmissions over a dedicated circuit, they packetize the transmissions with self-contained addresses that are then uploaded through a gateway into the network where they are relayed between routers until they reach their final destination. This packetization of transmissions allows for much more efficient transport of transmissions since empty space in a transmission (where no information is present) can be filled by additional transmissions. The problem with IP transmission, is that the packetization of data can lead to the degradation of voice and other transmissions that contain fairly constant streaming content and rely on high quality transport.
Voice over IP technology (VoIP) refers to technology allowing the signals generally broadcast over a PSTN network (such as, but not limited to, voice telephony, fax transmission, conference calling, voice mail, and similar transmissions) to be transmitted on an IP system using Internet protocol. More generally, VoIP is a method for packet-switch telephony. VoIP is now being used to build multiservice networks which bridge PSTN and IP-networks. Examples of such services are IP fax, messaging services such as unified messaging, Internet call managers, find-me-follow-me services, toll bypass long distance services, and PC telephony, all of which are gaining increasing acceptance and are becoming increasingly common.
As VoIP comes into increasing use, it also brings problems that were not present in the original PSTN system. One of these is the allocation of bandwidth on the IP-system. Traditionally, a service provider using PSTN would purchase a certain number of connections they were allowed to use. Since the PSTN network relied on dedicated connections, it was a simple matter to allocate a certain number of connections from the total available to any service provider. That service provider knew how many end-users they could have using the system at any time since they knew how many dedicated connections they could have. Each connection was a physical line would allow the connection to one individual, or to a certain limited number of individuals, using methods known in the art. When the lines are full, there is no way to accommodate additional end-users and another end-user attempting to use the lines will not be able to connect their call. This meant that a particular service provider could only use the number of connections they had acquired. A benefit of this system is that a network administrator could guarantee a service provider access to a specific number of connections and thereby guarantee the service provider could have that number of calls going on simultaneously. A service provider with too many simultaneous calls would lose those calls over this number of connections instead of taking connections guaranteed to another service provider.
In IP technology, there are no predetermined number of dedicated connections available for use by the service provider, instead there is a certain amount of bandwidth that can be shared. This lack of dedicated connections allows for efficient transmission of data across the network because the data can wait for available bandwidth and fill any available bandwidth, but it makes it difficult to handle VoIP network allocation to service providers. In particular, since there are no predefined connections, if additional end-users access the system resulting in more simultaneous calls than connections purchased by the service provider, those calls will still be able to connect and will take up the bandwidth allocated to another service provider. In an extreme case, this means that service providers can hog the bandwidth of other service providers preventing those other service providers from accessing the system they are supposed to have acquired rights to. Further, the hogging service provider may not have to pay any cost for its hogging, paying only for those connections it acquired. This ability of a service provider to use extra bandwidth means that a network administrator cannot guarantee a number of potential call connections making availability of the system unclear. To further aggravate the problem, the network administrator lacks an efficient method of monitoring an IP network for whether a particular service provider has additional end-users using additional connections because there are no set connections to monitor. Therefore, a service provider hogging the system may not even be aware of their overuse and have no indication that they should purchase additional capacity.
To prevent this problem, many VoIP systems have turned to monitoring by minutes of use instead of by calls or transmissions. This can be an effective way to prevent failure to pay for the network use actually used, but still does not allow the network administrator to guarantee the availability of connections to any particular service provider at any particular time or to prevent a service provider from hogging the network. This method merely insures that the service providers are charged for the additional services they use. This method is also problematic because it is unintuitive. VoIP systems handle calls and other traditional PSTN services which have always been measured in terms of number of calls and connections used. In order to compute needed minutes, service providers need to come up with new allocation systems to insure purchase of sufficient allocation.
To be able to guarantee a certain amount of call capacity to a particular service provider, a network administrator could allocate call capacity for different purposes by reserving dedicated access circuit capacity between the PSTN and the VoIP gateways for each service or for each service provider. This is a very inefficient way to allocate bandwidth, because it means that there is a dedicated access network for each service provider and the network administrator effectively recreates the system of the PSTN physical line limitations. To put it another way, the system has dedicated connections for use by each of the subscribers. Although this solves the above allocation problem, it also eliminates the benefits of VoIP technology. It does not allow the transfer of additional requirements to available additional resources.
The use of dedicated access circuits further results in a very costly and inefficient network. It could require allocating additional capacity to a service or for a service provider only by physically adding circuit capacity or changing gateway configuration to shift capacity from one service to another. This eliminates a further benefit of the IP network where all services and all service providers can share the same access network and the network itself is able to allocate capacity for different purposes in real-time without reconfiguring equipment or rearranging circuits.
It is therefore desirable in the art to have a method to allocate the use of connections in a way similar to that accomplished by the physical separation of lines, while at the same time, allowing capacity to utilize unused resources, allow quick modification of existing service provider capacities, and generally utilize the benefits of IP-networks. Both the avoidance of overuse and hogging of network resources and the availability of idle lines to be used for otherwise missed calls can allow the network to be allocated more efficiently.